Optical fiber sensor for atmospheric reentry experiments
Notice bibliographique
Résumé
Reliable temperature measurements of hot structures of re-entry vehicles is one of the main challenges associated with atmospheric heating. During re-entry, several minutes at hypersonic velocities results in severe aerothermal loads and a resultant temperature increase of more than 1000°C. In contrast to single-point measurements provided by thermocouples, optical fiber sensors allow temperature measurement at multiple positions along the fiber line. Key challenges of this technique include packaging, integration and extraction of the temperature contribution from a signal that is also influenced by strain effects. MPBC developed optical fiber sensors for such temperatures with special packaging optimizing between protective capability and fast thermal conductivity. The fiber sensors were initially calibrated with thermocouples using a standard oven, then by means of a test in the DLR arc-heated wind tunnel L3K at a material temperature of 1000°C. To well monitor the fast heat fluxes in reentry two special ruggedized interrogation modules (Interrogator) was developed with a data acquisition at 100 Hz and 3.5 kHz. The Interrogators have large memory capacity to save data during 1 hour, and a USB memory stick as back up. The Interrogators was validated for vacuum, thermal cycling and vibrations, being completely functional during the tests. The vibrations tests were successful even an accurate sweeping part the piezo of the tunable Fabry-Perot Interferometer was sweeping during the vibrations in X, Y and Z-axis. DLR integrated both 100 Hz and 3.5 kHz into the hypersonic flight experiment ATEK for measuring temperature distribution of the motor case of the second stage motor and hybrid module structure, respectively. The 3.5 KHz Interrogator was integrated in the hybrid module, which was part of the launcher block equipped with a parachute. The second stage performed the return flight without parachute and allowed testing the impact resistance of the new DLR’s data acquisition system and some measurement techniques. The ATEK flight experiment was successfully launched on 13th July 2019 from the launch site Esrange in Kiruna. The second stage and the payload reached an apogee of approx. 240 km and continued the descent without any thrust and landed approx. 500 seconds after the take-off at a distance of approx. 67 km from the launch site. The Health Monitoring System allowed the measurement of aerothermal and mechanical loads on the hybrid payload structure and the motor case along the complete flight. Part of the data has been transmitted during flight to ground via telemetry at a low sampling rate of several Hertz. In addition, several impact-resistant data acquisition units could acquire the data at a high sampling rate of several Kilohertz and stored it onboard. The housing of interrogator and memory stick box was nearly completely undamaged. All four fiber optic connectors were still attached. MPB will recuperate and evaluate its functionality. The 100Hz Interrogator, without protection, impacted the ground with a velocity of about 95 m/s and was damaged due to the impact
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».